1. Field of the Invention
The present invention relates to a tilt preventing structure for an electromagnetic driving device. The tilt preventing structure comprises a guiding mechanism comprising a magnetically susceptible material and a magnet disposed on a lens assembly. The magnet exerts a magnetic attraction force upon the guiding mechanism to reduce a dynamic tilt of the lens assembly during its movement along the guiding mechanism and thereby enable the lens assembly to move steadily.
2. Description of the Prior Art
Referring to FIG. 1, there is shown an exploded perspective view of a conventional zooming or focusing lens. A mechanical-transmission focusing mechanism 9 for use with a conventional focusing lens employs a high-cost precise driving element 91 (such as a stepper motor, an ultrasonic motor, or a piezoelectric actuator) to function as a power source for driving a support 93 having a lens assembly 92 and employs plenty of transmission elements, thereby resulting in a complicated mechanical structure, an intricate and difficult assembly process, an excessive volume, high costs, excessive power consumption, and a lack of price competitiveness.
In the early stage of the photography art, large human labor has been involved in metering, focusing and winding. Inevitably, it can be foreseen that how sorry would be if meeting a human mistake in taking photos in an important scene. Obviously, a quality photographer is the only answer to ensure photographing during such an important scene. Yet, it is well known that no 100% photographer is available anywhere and anytime. In the 50's and 60's, a great step has been achieved in the mechanical automation, from which people believe that automation would be the key to the future world. At that time, in the photography art, various developments such as the auto-metering device, the electrical winding apparatus and so on, have convinced people that automation is the future to the photography art. Among these developments, the development in the automatic focusing system who ensures the possibility of rapid photo-taking plays an important part.
Along with the technology development, conventional photographic apparatus has been progressed both in photographing quality and in the miniaturized appearance. However, the mechanical focusing lens set driven by the step motor hinders a further reduction in occupation of the apparatus
On the other hand, electromagnetic technology has also been introduced to improve the VCM electronic feedback system in monitoring the bias of the coil, which can replace the conventional step motor and provide a size down in the driving mechanism. Another development of the photography art is to add the photographic function to the other apparatus; for example, the integration of the photographic unit to the mobile phone, the PDA, the notebook computer and so on. All these changes make the current electronic merchandises equipped with a photographic unit that enhances a powerful video application to these aforesaid apparatuses.
Nevertheless, the aforesaid mobile phone, PDA, notebook computer, and the like portable electronic apparatus all have limitations in the battery capacity. Therefore, in aiming at the future of the photography art, the devotion upon how to design a low-energy-consumed driving device for focus or zoom lens set and how to anchor the lens set while the power is off is definitely welcome to the skilled person in the art.
Furthermore, all conventional lens driving devices are equipped with a guiding mechanism for guiding a lens to perform linear reciprocating displacement in a predetermined direction. To prevent the lens from getting stuck during its movement or proceeding with jerks and jolts, every conventional guiding mechanism always has an appropriate allowance (i.e., clearance) between its movable part and non-movable part (such as an axle hole and an axle). However, the clearance accounts for a slight quiver or a dynamic tilt that occur to the lens while at rest or in motion. The clearance increases with the tolerance of the axle hole to the detriment of the imaging quality of the lens or the precision in the positioning of the lens in motion. Accordingly, there is still room for improvement in the prior art.